A faint object rides the horizon
Department of War, Indo-PACOM, 2024.
The clip pans down to mast-like structures, which may be more informative than the sky. It suggests the sensor was looking near a cluttered environment. That context makes ordinary explanations important.
From the file
Visual note: The grayscale IR/EO sensor footage panning from featureless hazy sky down to a surface populated with many dark, thin vertical mast-like structures.